This invention pertains to magnetic resonance applications where focal phase deviations of the transverse magnetization are produced e.g.: by applied electrical energy, as in Magnetic Resonance Electrical Impedance Mammography, by metabolically induced susceptibility variations, as in Functional Magnetic Resonance Brain Imaging, or by local deviations in the intensity of the main magnetic B0 field.
Suppression of dephasing produced by local deviations in the main magnetic field by successive radio frequency (r.f.) pulses was discovered by Hahn. [Hahn, E. L. Phys. Rev. 80, 580, (1950)] (which is hereby incorporated by reference in its entirety). Image formation in magnetic resonance imaging can be performed by multi-dimensional Fourier methods [Kumar, A; Welti, D; Ernst, R. R.: J. Magn Reson. 18, 69 (1975)] (which is hereby incorporated by reference in its entirety), by single sweep “echo-planar” methods [Mansfield, P; J. Phys. C10, L55 (1977)] (which is hereby incorporated by reference in its entirety), or by combinations and permutations thereof.
Phase sensitive detection is well-known in radio communication [Dorf, R. C., “The Electrical Engineering Handbook”, IEEE CRC Press, Boca Raton, Fla., 1993, Ch. 63] (which is hereby incorporated by reference in its entirety) and in magnetic resonance image formation [Liang, Z.; Lauterbur, P. C., “Principles of Magnetic Resonance Imaging” IEEE Press, New York, 2000, p. 99, Ch. 3] (which is hereby incorporated by reference in its entirety), as are spatially orthogonal coil sets and generalizations to bird-cage multi-phase coils [Cho, Z.; Jones, J. P.; Singh, M., “Foundations of Medical Imaging”, John Wiley & Sons, New York, 1993] (which is hereby incorporated by reference in its entirety). Phase sensitive detection resolves the received signal into real even (cosine) and imaginary odd (sine) components with respect to the magnetic resonance (MR) machine radio frequency (r.f.) generator creating magnitude and phase maps as in Miyoshi (U.S. Pat. No. 6,774,629) (which is hereby incorporated by reference in its entirety). Phase difference reconstruction to produce a phase difference map is known prior art in magnetic resonance imaging requiring manipulation of two or more independently acquired complex data sets. [Bernstein, M. A., King, K. F., Zhou, X. J., “Handbook of MRI Pulse Sequences”, Elsevier Academic Press, Oxford, U.K., 2004, Ch 13.5, (e.g. FIG. 13.34)] (which is hereby incorporated by reference in its entirety).